Ball joints are commonly employed in rigid conduit or duct systems where it is desired that the systems have a degree of flexibility yet remain leak proof. Such joints consist of ball and socket elements each adapted to be connected to a conduit, and the ball element has a partial spherical end received within a corresponding spherical socket cavity defined in on end of the other element, thus permitting a degree of relative universal angular movement between the elements and the associated conduits. A spring member, usually in the form of a wave washer or a conical compression spring, is often interposed between the ball and socket elements to insure electrical continuity between the elements as they are angularly displaced to eliminate the potential build-up of static electricity.
While ball joints of this type incorporate a relatively simple construction and may be quickly and easily assembled, some deficiencies have been experienced. For instance, because the spring member compresses and expands as the elements are angularly displaced, a spring biasing force is applied to the elements tending to cause the elements to co-axially re-align which defeats the purpose of the ball joint. Also, because the axial length of the ball and socket spherical configurations must necessarily be limited to permit assembly, the angular adjustment of the associated conduits is relatively limited as a fluid-tight relationship between the elements must always be maintained.
It is an object of the invention to provide a ball joint for conduits including a pair of spherical elements pivotally mounted within a spherical segment cavity to form a "ball within a ball" relationship which permits twice the angular conduit deflection of a typical ball joint.
It is a further object of the invention to provide a ball joint for rigid conduit or duct systems consisting of a ball/socket element for one conduit having a partly spherical outer surface adapted to be pivotally received within a spherical cavity defined in a housing member and a spherical inner surface receiving a ball element of the other conduit whereby a "double" ball and socket relationship exists providing an increased range of conduit angular adjustment.
An additional object of the invention is to provide a ball joint for conduits consisting of an element having a partly spherical ball end adapted to be pivotally received within the partially spherical cavity of another element and a spring member maintaining electrical continuity between the elements is affixed to the ball element and is of such configuration that the spring member "rocks" when the ball joint is articulated providing a substantially constant spring load at all conduit angular positions.
Still another object of the invention is to provide a "double" ball joint including an outer housing having pressure ports defined thereon which allow the housing to be pressurized to check the condition of the primary seals.
In the practice of the invention the ball joint consists of a pair of elements each adapted to be connected to an end of a conduit. Both of the elements include a spherical segment outer surface and a spherical segment cavity, and one of the elements is adapted to be closely received within the spherical cavity of the other, thus permitting universal angular displacement between the associated conduits. The elements are encompassed by an annular housing which includes a pair of axially spaced and aligned spherical segment sealing surfaces adapted to pivotally receive one of the elements' outer spherical surface. Sealing rings located within annular grooves defined in the sealing surfaces establish a sealing engagement with the associated elements, outer spherical surface.
The housing is provided with pressure check ports having passages in communication with the interior of the housing and the sealing rings, and the ports are adapted to be connected to a pressurized test apparatus allowing the housing to be pressurized to check the condition of the sealing rings whereby if leakage occurs replacement of the sealing rings is indicated.
The mounting of a ball and socket joint within the housing such that the housing sealing surfaces engage the exterior of both the socket and ball permits the joint of the invention to be articulated to an extent twice that of a conventional conduit ball joint and yet a concise configuration can still be maintained.
A spring member formed of a wire element is interposed between the inner ball and socket elements to provide electrical continuity therebetween. The spring member is of an oblong bowed configuration including a pair of legs which have an arcuate configuration, and, preferably, the spring member is affixed to the inner ball element to maintain the spring position during assembly and use and as the inner ball and socket elements are angularly displaced the spring "rocks" providing a substantially constant spring load.